Nov 25

Written by:
11/25/2011 11:01 AM 

Solar heating for homes is so neglected that the Beachcomber can assume all solar energy is photoelectric; check the column head in the November 23 issue. Unfortunately the Beachcomber has it backwards. Most of the collectable energy is thermal. The reason for the misunderstanding is pizzazz. A photoelectric system installs readily and looks impressive. A thermal system is difficult to install. Does that excuse putting up panels we don’t need while thumping the solar drum? No, instead it hampers real progress. The “solar sites” making the front page of the Beachcomber are a sucker punch to the gut of solar heating. My, how sloppy can a blog get.

At present, solar tap water heating systems are highly developed. and are widely used in Canada. Vashon’s Blue Ridge company does not handle these. On the other hand solar hot water space heating is poorly developed, and a rare hit on the internet. The reason is that radiators for low temperature water are poorly developed. Solar hot water is not much hotter than tap hot water, consequently the radiators have to be much larger. These are not available. The point of this blog is that the needed radiators are feasible.

Also holding back space heating with solar hot water in the US is the inertia of the US hot water industry in regard to the heat transfer fluid: the fluid has to flow in a loop closed to contamination by mains water. The quite valid reason is that the high temperature that is standard for a hot water heated house would cause mains water, rich in oxygen and crud, to degrade the pipes. But this precaution need not apply to solar hot water which is warmer: as proof, tap hot water tanks carry twenty-year warranties --  on mains water. The upshot of this “inertia” is a doubling of space heat cost for a closed loop delivery system versus one using mains water.  The Canadian solar collector is designed to run on mains water, warranted for twenty years.

Hey, Bill, hey Gib, hey, Beachcomber, solar HEAT is what’s needed.